Problems B
155
(a) 0.520 g of NiSO 4 -.vH,O gave a residue of 0.306 g
(b) 0.895 g of MnI 2 -.vH,O gave a residue of 0.726 g
(c) 0.654 g of MgSCV.v H 2 O gave a residue of 0.320 g
(d) 1.216 g of CdSO 4 -.vH,O gave a residue of 0.988 g
(e) 0.783 g of KAl (SO 4 ) 2 -.vH 2 O gave a residue of 0.426 g
20. Weighed samples of the following metals are completely converted to compounds by heating them in the presence of the specified elements, and then are
reweighed to find the increase in weight. The excess of the nonmetal is easily
removed in each case. From the data given find the formulas of the compounds formed.
(a) 0.753 g of Ca gave a 0.792 g residue with H 2
(b) 0.631 g of Al gave a 1.750 g residue with S
(c) 0.137 g of Pb gave a 0.243 g residue with Br 2
(d) 0.211 g of U gave a 0.249 g residue with O 2
(e) 0.367 g of Co gave a 0.463 g residue with P
21. The following values of isotopic weights and abundances are obtained with a
mass spectrometer. Compute the chemical atomic weights for the elements
involved. The isotopic weights are in parentheses.
(a) For magnesium: 78.70% (23.98504), 10.13% (24.98584), and 11.17%
(25.98259).
(b) For titanium: 7.95% (45.9661), 7.75% (46.9647), 73.45% (47.9631), 5.51%
(48.9646), and 5 34% (49.9621).
22. A metal forms two different chlorides. Analysis shows one to be 40.3% metal
and the other to be 47.4% metal by weight. What are the possible values of the
atomic weight of the metal?
23. A sample of an organic compound containing C, H, and O, which weighs
12.13 mg, gives 30.6 mg of CO 2 and 5.36 mg of H 2 O in combustion. The
amount of oxygen in the original sample is obtained by difference. Determine
the empirical formula of this compound.
24. A 5.135 g sample of impure limestone (CaCO 3 ) yields 2.050 g of CO 2 (which
was absorbed in a soda-lime tube) when treated with an excess of acid. Assuming that limestone is the only component that would yield CO 2 , calculate
the percentage purity of the limestone sample.
155
(a) 0.520 g of NiSO 4 -.vH,O gave a residue of 0.306 g
(b) 0.895 g of MnI 2 -.vH,O gave a residue of 0.726 g
(c) 0.654 g of MgSCV.v H 2 O gave a residue of 0.320 g
(d) 1.216 g of CdSO 4 -.vH,O gave a residue of 0.988 g
(e) 0.783 g of KAl (SO 4 ) 2 -.vH 2 O gave a residue of 0.426 g
20. Weighed samples of the following metals are completely converted to compounds by heating them in the presence of the specified elements, and then are
reweighed to find the increase in weight. The excess of the nonmetal is easily
removed in each case. From the data given find the formulas of the compounds formed.
(a) 0.753 g of Ca gave a 0.792 g residue with H 2
(b) 0.631 g of Al gave a 1.750 g residue with S
(c) 0.137 g of Pb gave a 0.243 g residue with Br 2
(d) 0.211 g of U gave a 0.249 g residue with O 2
(e) 0.367 g of Co gave a 0.463 g residue with P
21. The following values of isotopic weights and abundances are obtained with a
mass spectrometer. Compute the chemical atomic weights for the elements
involved. The isotopic weights are in parentheses.
(a) For magnesium: 78.70% (23.98504), 10.13% (24.98584), and 11.17%
(25.98259).
(b) For titanium: 7.95% (45.9661), 7.75% (46.9647), 73.45% (47.9631), 5.51%
(48.9646), and 5 34% (49.9621).
22. A metal forms two different chlorides. Analysis shows one to be 40.3% metal
and the other to be 47.4% metal by weight. What are the possible values of the
atomic weight of the metal?
23. A sample of an organic compound containing C, H, and O, which weighs
12.13 mg, gives 30.6 mg of CO 2 and 5.36 mg of H 2 O in combustion. The
amount of oxygen in the original sample is obtained by difference. Determine
the empirical formula of this compound.
24. A 5.135 g sample of impure limestone (CaCO 3 ) yields 2.050 g of CO 2 (which
was absorbed in a soda-lime tube) when treated with an excess of acid. Assuming that limestone is the only component that would yield CO 2 , calculate
the percentage purity of the limestone sample.